#include<stdio.h>

int main(){
	int matrix[][3] = { {1, 2, 3}, {4, 5, 6}, {7, 8, 9} };
	int sum = 0;
	for(int i = 0; i < 3; i++)
		sum += matrix[i][i];
	printf("%d", sum);
	return 0;
}
